Mumford & Sons are unlikely pop stars. The four British musicians wielding traditional folk instruments like banjos and mandolins somehow managed to break into the American mainstream.

They attracted a huge crowd to CMAC on August 7 and entertained with an energized show.

Singer-songwriter Aaron Embry opened the triple-billed show with an acoustic set. Alone on the stage, the barefoot Embry plucked a four-string tenor guitar. His melodic picking recalled classic country, but his solemn harmonica was pure Neil Young.

After Embry, California rock band Dawes took the stage. The group looked straight from the ’70s – shaggy hair and button-up shirts tucked into their jeans – and sounded like it, too. Singer/guitarist Taylor Goldsmith lays on thick Jackson Browne hooks with Byrds-style guitar riffs that create a warm California sound popularized by the aforementioned bands. As they played their first few songs, “Time Spent in Los Angeles” and “Coming Back to a Man,” people flooded in, as if drawn to their music.

Goldsmith was the only guitarist in the four-piece band, but bassist Wylie Gelber and keyboard player Tay Strathairn round out the music, filling the gaps during guitar solos. He usually sang memorable, simple melodies, but Goldsmith often showed he could really belt out his songs, too. His brother Griffin, the group’s drummer, and Straithairn also threw their voices in on “Fire Away.” Each of the singers took a vocal solo before coming together in a three-part harmony.

Dawes played a new song from their upcoming third album, followed by the heartfelt “A Little Bit of Everything.” They closed with “When My Time Comes,” with help from Marcus Mumford on vocals and guitar.

Following a short break, Mumford returned to the stage with his bandmates, Ben Lovett, Winston Marshall and Ted Dwane. They began playing a new song, “Lover’s Eyes,” on a dark stage. Mumford softly strummed his acoustic guitar before both the music and lights erupted. As the stage lit up momentarily, so did the crowd, but even in the dark, “Lover’s Eyes” kept building – Mumford pounding the bass drum at his foot, and Marshall furiously picking his banjo.

When the song fell to a close, they went into one of their biggest hits, “Little Lion Man.” The group’s four members stood in a straight line across the stage, now permanently lit. Hanging lightbulbs, strung from the rafters, illuminated the arena.

Mumford & Sons played most of the songs from their debut album, Sigh No More, and a handful of new ones. While the earlier tracks were often boisterous stompers, the newer material finds them growing into their mainstream success.

Mumford sat behind a drum set to sing a few songs and Marshall exchanged his banjo for electric guitar, but the band hasn’t completely abandoned folk rock in favor of mid-tempo pop music. Their new single, “I Will Wait,” had the energy and pounding bass drum of songs from Sigh No More.

They invited Dawes back onstage for “Awake My Heart,” before closing with “Dust Bowl Dance.” Their encore included the horn-heavy “Winter Winds” and a new song, “Where Are You Now?,” but the obvious favorite was the finale, the massively successful single “The Cave.”

Mumford & Sons’ formula for a pop hit is a strange one. Folk instruments and harmonies don’t really make platinum records anymore, but they blew past expectations for mainstream success. It doesn’t necessarily make sense, but it sounds fantastic.